Synergistic Antibacterial Properties Research Articles

Synergistic Antibacterial Properties of Silver Nanoparticles and Its Reducing Agent from Cinnamon Bark Extract.

Synthesis of silver nanoparticles with antibacterial properties using a one-pot green approach that harnesses the natural reducing and capping properties of cinnamon (Cinnamomum verum) bark extract is presented in this work. Silver nitrate was the sole chemical reagent employed in this process, acting as the precursor salt. Gas Chromatography-Mass Spectroscopy (GC-MS), High-Performance Liquid Chromatography (HPLC) analysis, and some phytochemical tests demonstrated that cinnamaldehyde is the main component in the cinnamon bark extract. The resulting bio-reduced silver nanoparticles underwent comprehensive characterization by Ultraviolet-Vis (UV-Vis) and Fourier Transform InfraRed spectrophotometry (FTIR), Dynamic Light Scattering (DLS), Transmission Electron Microscopy, and Scanning Electron Microscopy suggesting that cinnamaldehyde was chemically oxidated to produce silver nanoparticles. These cinnamon-extract-based silver nanoparticles (AgNPs-cinnamon) displayed diverse morphologies ranging from spherical to prismatic shapes, with sizes spanning between 2.94 and 65.1 nm. Subsequently, the antibacterial efficacy of these nanoparticles was investigated against Klebsiella, E. Coli, Pseudomonas, Staphylococcus aureus, and Acinetobacter strains. The results suggest the promising potential of silver nanoparticles obtained (AgNPs-cinnamon) as antimicrobial agents, offering a new avenue in the fight against bacterial infections.

Accelerated in-vivo infected dermal wound healing with antimicrobial Bio-nanocomposite hydrogel

Infected wounds pose significant challenges in clinical settings due to the risk of complications and delayed healing of wounds. The most common wound dressings are cotton balls and gauze, and yet these traditional wound dressings have inherent shortcomings including low antibacterial properties, less oxygen permeation, mechanical properties, and moisture content essential for wound healing of infected wounds. Herein, we fabricate polyvinyl alcohol/chitosan/pectin (PVA/CH/PEC) hydrogel loaded with green-synthesized nanometals, and synthetic antibiotics for the treatment of infected wounds with enhanced mechanical properties, synergistic antibacterial properties, higher moisture, and oxygen permeation content. The silver nanoparticles (AgNPs), synthesized via sea buckthorn leaf extract, and ciprofloxacin were incorporated in the bio-nanocomposite hydrogels. The particle size of AgNPs was found to be in the range of 15 to 42 nm. The synthesized bio-nanocomposite hydrogels confirm its biocompatible nature because of reduction in the percentage hemolysis from 1.7% to 1.4% and cell viability exceeding 87% in PVA/CH/PEC and poly vinyl alcohol/chitosan/pectin–Silver/ ciprofloxacin (PVA/CH/PEC-Ag/cipro) hydrogel membranes, respectively. Microscopic observation of PVA/CH/PEC/Ag-Ciprofloxacin hydrogels demonstrated the last stages of regeneration and skin reformation towards normal skin as compared to hydrogel scaffold without ciprofloxacin. The hydrogel promoted advanced stages of regeneration and skin reformation, signifying its potential as a promising dressing material for infected wound healing applications.

Phase Change Material-Embedded Multifunctional Janus Nanofiber Dressing with Directional Moisture Transport, Controlled Release of Anti-Inflammatory Drugs, and Synergistic Antibacterial Properties.

Wound healing is a systematic and complex process that involves various intrinsic and extrinsic factors affecting different stages of wound repair. Therefore, multifunctional wound dressings that can modulate these factors to promote wound healing are in high demand. In this work, a multifunctional Janus electrospinning nanofiber dressing with antibacterial and anti-inflammatory properties, controlled release of drugs, and unidirectional water transport was prepared by depositing coaxial nanofibers on a hydrophilic poly(ε-caprolactone)@polydopamine-ε-polyl-lysine (PCL@PDA-ε-PL) nanofiber membrane. The coaxial nanofiber was loaded with the phase change material lauric acid (LA) in the shell layer and anti-inflammatory ibuprofen (IBU) in the core layer. Among them, LA with a melting point of 43 °C served as a phase change material to control the release of IBU. The phase transition of LA was induced by near-infrared (NIR) irradiation that triggered the photothermal properties of PDA. Moreover, the Janus nanofiber dressing exhibited synergistic antimicrobial properties for Escherichia coli and Staphylococcus aureus due to the photothermal properties of PDA and antibacterial ε-PL. The prepared Janus nanofiber dressing also exhibited anti-inflammatory activity and biocompatibility. In addition, the Janus nanofiber dressing had asymmetric wettability that enabled directional water transport, thereby draining excessive wound exudate. The water vapor transmission test indicated that the Janus nanofiber dressing had good air permeability. Finally, skin wound healing evaluation in rats confirmed its efficacy in promoting wound healing. Therefore, this strategy of designing and manufacturing a multifunctional Janus nanofiber dressing had great potential in wound healing applications.

Solar-induced self-healing superhydrophobic masks with photo-sterilization and reusability

Personal protective masks have been widely recommended to mitigate the transmission of respiratory diseases during a pandemic outbreak. However, common surgical masks cannot be self-sterilized for reuse, resulting in the increasing potential risk of second infection and higher economic costs. Herein, the solar-induced self-healing superhydrophobic mask (PCNTs-HD8) with excellent photo-sterilized and reusable capabilities is fabricated by a simple spraying technology. The PCNTs-HD8 exhibits remarkable superhydrophobic and photothermal properties, enabling the potent synergistic antibacterial effects against both Gram-positive Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. Benefiting from the excellent solar-induced self-healing superhydrophobic properties, PCNTs-HD8 shows potential for reusable without losing the efficient synergistic antibacterial properties even after undergoing 12 times of etching-healing cycles. The PCNTs-HD8 also maintains almost the same water vapor transport rate compared with pristine surgical masks. This work provides an immediate strategy to mitigate the transmission of respiratory diseases while reducing economic costs and resource consumption.

A multifunctional superhydrophobic coating with efficient anti-adhesion and synergistic antibacterial properties

Bacterial adhesion and colonization on the surface present a public health concern worldwide. To address this concern, surfaces are endowed with the ability to resist bacterial adhesion to surfaces and eliminate bacteria. In this study, a multifunctional superhydrophobic antibacterial surface is prepared by combining two composite fillers obtained by in-situ growth of silica nanoparticles on palygorskite via sol-gel and modified by a low surface energy substance and by in-situ reduction of silver nanoparticles via tannic acid and thus adhering to the palygorskite and modified by the low surface energy substance, reducing bacterial adhesion and survival in multiple ways. Firstly, the complex nano/micro structures and low surface energy of the superhydrophobic surface hinder protein adhesion and bacterial adhesion on the surface. Secondly, the sharp surfaces constructed by the nanofibers disrupt bacterial cell integrity, providing physical antibacterial action. Thirdly, the coating releases silver ions and reactive oxygen species, which are produced by silver nanoparticles, to chemically damage bacteria. Through the synergy of superhydrophobic surface and silver nanoparticles, the coating achieves good resistance to bacterial adhesion and is able to eliminate Escherichia coli (100.0 ± 0.1 %) and Staphylococcus aureus (99.8 ± 0.1 %). The coating also exhibits good mechanical properties, with silver ions still being released after 100 cycles of wear test. With its unique self-cleaning, anti-adhesive, anti-corrosion, robust mechanical properties, and antibacterial capabilities, the superhydrophobic coating holds a promising application prospect.

Antibacterial effects of quercetagetin are significantly enhanced upon conjugation with chitosan engineered copper oxide nanoparticles.

The development of antibiotic alternatives that entail distinctive chemistry and modes of action is necessary due to the threat posed by drug resistance. Nanotechnology has gained increasing attention in recent years, as a vehicle to enhance the efficacy of existing antimicrobials. In this study, Chitosan copper oxide nanoparticles (CHI-CuO) were synthesized and were further loaded with Quercetagetin (QTG) to achieve the desired (CHI-CuO-QTG). Size distribution, zeta potential and morphological analysis were accomplished. Next, the developed CHI-CuO-QTG was assessed for synergistic antibacterial properties, as well as cytotoxic attributes. Bactericidal assays revealed that CHI-CuO conjugation showed remarkable effects and enhanced QTG effects against a range of Gram + ve and Gram-ve bacteria. The MIC50 of QTG against S. pyogenes was 107µg/mL while CHI-CuO-QTG reduced it to 9µg/mL. Similar results were observed when tested against S. pneumoniae. Likewise, the MIC50 of QTG against S. enterica was 38µg/mL while CHI-CuO-QTG reduced it to 7µg/mL. For E. coli K1, the MIC50 of QTG was 42µg/mL while with CHI-CuO-QTG it was 23µg/mL. Finally, the MIC50 of QTG against S. marcescens was 98µg/mL while CHI-CuO-QTG reduced it to 10µg/mL. Notably, the CHI-CuO-QTG nano-formulation showed limited damage when tested against human cells using lactate dehydrogenase release assays. Importantly, bacterial-mediated human cell damage was reduced by prior treatment of bacteria using drug nano-formulations. These findings are remarkable and clearly demonstrate that drug-nanoparticle formulations using nanotechnology is an important avenue in developing potential therapeutic interventions against microbial infections.

Synergistic Antibacterial Surface with Liquid Repellency and Enhanced Photothermal Bactericidal Activity.

The presence of microorganisms on biomedical devices and food packaging surfaces poses an important threat to human health. Superhydrophobic surfaces, a powerful tool to combat pathogenic bacterial adhesion, are threatened by their poor robustness. As a supplement, photothermal bactericidal surfaces may be expected to kill adhered bacteria. Using copper mesh as a mask, we prepared a superhydrophobic surface with a homogeneous conical array. The surface shows synergistic antibacterial properties, including a superhydrophobic character against bacterial adhesion and photothermal bactericidal activity. As a result of the excellent liquid repellency, the surface could highly repel the adherence of bacteria after immersing in a bacterial suspension for 10 s (95%) and 1 h (57%). Photothermal graphene can easily eliminate most adhered bacteria during the subsequent treatment of near-infrared (NIR) radiation. After a self-cleaning wash, the deactivated bacteria were easily rinsed off the surface. Furthermore, this antibacterial surface exhibited an approximately 99.9% resisted bacterial adhesion rate regardless of planar and various uneven surfaces. The results offer promising advancement of an antibacterial surface combining both adhesion resistance and photothermal bactericidal activity in fighting microbial infections.

High-performance films fabricated by food protein nanofibrils loaded with vanillin: Mechanism, characterization and bacteriostatic effect

A viable platform for food packaging applications has evolved in the form of protein nanofibers with material properties. Through this work, a simple, extensible process of protein for amyloid fibrils formation was proposed. The addition of polyphenol was expected to improve its synergistic antibacterial properties. The isolate protein of soy and whey (SPI and WPI) were selected as model proteins with an acid-heat treatment for 5 h to prepare the nanofibrils. Protein molecules eventually lost their intrinsic structure, which was also followed by aggregation and degeneration. Atomic force microscopy was used to investigate how proteins' spherical and linear shapes changed over time. As the protein unfolded and intermolecular aggregation occurred, circular dichroism (CD) demonstrated that the protein's secondary structure altered from a-helix to β-sheet and random coils. Furthermore, the fibrous protein films' mechanical characteristics were enhanced, particularly the elongation (E) of amyloid SPI films, which increased from 33.50 % to 100.57 %. Additionally, the films' water solubility (WS) and water vapor permeability (WVP) were both decreased. In order to create an antibacterial edible film, vanillin was also added to the fibrous protein solution as a bacteriostatic agent. The results showed that the fibrous protein film demonstrated a great bacteriostatic action and retained good shape. Here we present this simple and efficient method to obtain robust, flexible films, which not only provides a strategy for films with good mechanical properties but also extends their antibacterial by adding a bacteriostatic agent to further provide a new idea for food packaging.

Dissolving microneedles based on ZnO nanoparticles and an ionic liquid as synergistic antibacterial agents.

The use of nanomaterials to replace antibiotics has developed rapidly in the past decade, among which zinc oxide nanoparticles (ZnO NPs) have been proven to exhibit antibacterial properties and low toxicity in the treatment of microbial infections, and have been applied in antibacterial agent preparation. However, one of the problems of ZnO NPs is that these particles do not disperse well in some media, which reduces their antibacterial effects. Ionic liquids (ILs) are a class of low melting point salts containing organic cations and organic/inorganic anions; they have good biocompatibility and can not only enhance the dispersion of ZnO NPs but also have antibacterial properties. Microneedles (MNs) are an emerging transdermal drug delivery platform, which can effectively establish a transport channel in the epidermis and deliver the drug to a predetermined depth without causing pain, skin damage or overstimulation. Dissolving microneedles (DMNs) have developed rapidly because of several advantages. In this study, it is verified that ZnO NPs dispersed in the imidazolidinyl IL exhibit excellent and enhanced antibacterial effects compared with single ZnO NPs and a single IL. Therefore, ZnO NPs/IL dispersion showed good antibacterial activity. Then, ZnO NPs/IL dispersions with synergistic antibacterial properties were used as antibacterial agents to prepare DMNs. In vitro antibacterial results showed that DMNs also had good antibacterial properties. Furthermore, DMNs were applied to treat wound infection. Antibacterial DMNs were inserted into the infected wound and then dissolved and released, resulting in microbial death and acceleration of wound healing.

A MXene@AgAu@PDA nanoplatform loaded with AgAu nanocages for enhancing catalytic activity and antibacterial performance.

With the rapid development of social industrialization, environmental problems seriously threaten people's health, especially water pollution. Therefore, there is an urgent need to construct a multifunctional nanoplatform for different scenarios. Two-dimensional MXene@AgAu@PDA nanosheets loaded with AgAu bimetallic nanocages have been prepared by a one-step method. First, the in situ generated MXene@Ag is used as an auxiliary template, and then HAuCl4 and dopamine are added for in situ redox-oxidizing polymerization reactions to obtain AgAu catalytic nanocages and the protective polydopamine (PDA) layer which can improve the stability and biocompatibility. MXene and PDA have excellent photothermal conversion ability while hollow AgAu nanocages have strong absorption in the near-infrared region and a local surface plasmonic resonance effect. In comparison to the catalytic reaction rates under dark and room temperature conditions, the catalytic kinetic rate of MXene@AgAu@PDA nanosheets under near-infrared irradiation increases from 0.13 to 0.69 min-1 mg-1. Density functional theory (DFT) is used to study the electron transfer behavior between AgAu nanocages and MXene nanosheets, and the mechanism of the enhanced catalytic reaction rate is analyzed. Besides, due to its Ag ions and photothermal coupling antibacterial properties, 40 μg mL-1 MXene@AgAu@PDA nanosheets inactivates nearly all E. coli and S. aureus after irradiation with near-infrared light for 6 min.

Nitrosothiol-functionalized silicate bioceramic scaffolds with enhanced antibacterial property for bone repair

Bacterial infection is a challenge in the field of bone tissue engineering. Antibiotics are often used to combat infection, but the abuse of antibiotics causes nonselective cytotoxicity and induces bacterial drug resistance. Therefore, it is of great clinical significance to develop bone tissue engineering scaffolds with antibacterial properties for bone repair. In this study, polymer-derived β-Ca2SiO4 (C2S) scaffolds were functionalized with nitric oxide (NO) precursors to repair infected bone defects due to their synergistic antibacterial properties by combining a photothermal effect and NO gas therapy. The results showed that the functionalization of C2S scaffolds with NO precursors not only maintained the initial macropore structure and photothermal effect of the scaffolds, but also endowed the scaffolds with sustained NO release ability. Importantly, the NO precursor-functionalized C2S (C2S–SNO) scaffolds improved the proliferation and alkaline phosphatase (ALP) activity of bone marrow mesenchymal stem cells (rBMSCs), as well as the expression of related osteogenic genes. Furthermore, the photothermal effect of the C2S–SNO scaffolds and the NO release induced by near-infrared (NIR) laser irradiation contributed to enhanced antibacterial efficacy, and the inhibition efficiencies of the C2S–SNO scaffolds against Staphylococcus aureus and Escherichia coli were estimated to be approximately 83.3% and 87.5%, respectively. Therefore, the C2S–SNO scaffolds are promising for repairing infected bone defects.

Synergistic antibacterial properties of ZnO–SnO2 composite under both light and dark conditions

Antibacterial performance of photocatalytic materials is limited by their low utilization of visible light, rapid recombination of photocarriers, and dependence on light irradiation. ZnO–SnO2 composite photocatalytic antibacterial materials were synthesized by hydrothermal method with different molar ratios. Results showed that heterojunction structure was formed between ZnO and SnO2, improving lifetime of photocarriers and enhancing photocatalytic antibacterial performance. Meanwhile, dissolution of Zn2+ ensured strong antibacterial effect in the dark. When the addition amount of ZnO in the composite material was 40%, the best antibacterial effect was achieved, with bactericidal rate of Escherichia coli (E. coli) reaching more than 99% after 15 min illumination. Antibacterial mechanism of this photocatalyst was studied by inductively coupled plasma optical emission spectrometry (ICP-OES), electron paramagnetic resonance (EPR), fluorescence spectroscopy, and scavenger experiments. Results demonstrated that Zn2+ and reactive oxygen species (ROS) played vital role in antibacterial process. Moreover, ·OH was the most significant ROS. Compared with single-component photocatalytic antibacterial agents, ZnO–SnO2 composite demonstrated enhanced photocatalytic antibacterial performance as well as improved light utilization through synergistic sterilization effect of Zn2+ ions and enhanced ROS. These results have significant practical value for development of antibacterial photocatalysts.

Synergistic antibacterial photocatalytic and photothermal properties over bowl-shaped TiO2 nanostructures on Ti-19Zr-10Nb-1Fe alloy

As implant substitutes are increasingly applied to the clinic, the infection caused by implants has become one of the most common complications, and the modification of the antibacterial function of the implant can reduce such complications. In this work, a well-defined bowl-shaped nanostructure coating with photocatalytic and photothermal synergistic antibacterial properties was prepared on Ti-19Zr-10Nb-1Fe (TZNF) alloy. The coating is obtained by spin-coating and sintering TiO2 precursors templated from self-assembled microspheres of polystyrene-poly(4-vinylpyridine) (PS-P4VP) amphiphilic block polymer on TZNF alloy. PS-P4VP provides the bowl-shaped TiO2 nanostructures doped with C, N elements, reducing the band-gap of TiO2, which can absorb near-infrared (NIR) light to release reactive oxygen species and produce photothermal conversion. The bowl structure is expected to enhance the utilization of light via the reflection in the confined space. The bowl-shaped surface has 100% antibacterial rates after 30 min of NIR light irradiation. In addition to antibacterial properties, the bowl-shaped surface has better hydrophilicity and protein adsorption capacity. The amount of protein adsorbed on TZNF with the bowl-shaped structures was six times that of TZNF. Hence, the bowl-shaped nanostructure can promote the proliferation and adhesion of osteoblasts, the cell proliferation rate was increased by 10–30%.

Fabrication of Curcumin@Ag Loaded Core/Shell Nanofiber Membrane and its Synergistic Antibacterial Properties.

The core/shell structure nanofiber membrane loaded with curcumin and silver nanoparticles was prepared by coaxial electrospinning technology, which is a high-efficiency combined antibacterial material composed of photodynamic antibacterial agent and metal nanoparticle. As a photosensitizer, curcumin could generate singlet oxygen under laser irradiation. Silver nanoparticles have antibacterial properties, and could also enhance the singlet oxygen production of curcumin due to the metal-enhanced singlet oxygen effect, thereby producing a synergistic antibacterial effect. Compared with the antibacterial rate of uniaxial curcumin fiber membrane (45.65%) and uniaxial silver nanoparticle-loaded fiber membrane (66.96%), the antibacterial rate of curcumin@Ag core/shell structure fiber membrane against Staphylococcus aureus is as high as 93.04%. In addition, the antibacterial experiments show that the core/shell fiber membrane also has excellent antibacterial effects on Escherichia coli.

Self-healing polydimethylsiloxane antifouling coatings based on zwitterionic polyethylenimine-functionalized gallium nanodroplets

There is an urgent need to develop effective and eco-friendly nanostructured coatings for marine antifouling to replace traditional coatings, while ensuring they do not lead to environmental hazards. Gallium-based liquid metal (GLM), which has unique antibacterial and non-toxic properties, has potential for applications in antifouling. In this study, GLM nanodroplets modified with zwitterionic polymer (polyethylenimine-quaternized derivative, PEIS) based antifouling agent were prepared successfully via sonication and Michael-addition, which could potentially be incorporated into the polydimethylsiloxane coating (PDMS) as a functional filler. A series of characterization methods, such as infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy, have proved the successful modification of GLM nanodroplets with PEIS. The PEIS functionalized GLM nanodroplets exhibit good anti-bacterial properties due to synergistic bactericidal activity of Ga3+ stemming from GLM nanodroplets and the quaternary ammonium group from zwitterionic polymer PEIS. The synergistic anti-bacterial properties of PEIS-GLM nanodroplets and strong surface hydration of zwitterionic polymer PEIS result in remarkable antifouling performance of the filler. Subsequently, through the observation of the cross section, the as-prepared PEIS modified GLM nanodroplets exhibit good dispersibility in the PDMS coating, which also ensures that the PEIS-GLM@PDMS coating has satisfactory antifouling effect (removal of above 90% bacteria and 70% microalgae). Furthermore, the PEIS modified GLM nanodroplets endow the PDMS coating with self-healing properties by reason of the crosslinking of unreacted vinyl in PDMS by exposed GLM initiating polymerization under external mechanical force.

Gold nanosensor for the selective identification of Escherichia coli in foodstuff and its antibacterial ability

A promising gold nanorod sensor that demonstrated comparable antibacterial ability, selectively recognized Escherichia coli (E. coli), and used selenol as the recognition group was prepared and applied for foodstuff E.coli detection. We used a sulfhydryl compound linked with fluorescent dye by sulfamide bonds (SH-NB) to modify gold nanorods (GNRs) and fabricate GNRs-SH-NB that can selectively and sensitively detect selenol. Selenol group broke sulfamide bonds, causing the fluorescent dye to fall off from GNRs-SH-NB and exhibit red fluorescence, demonstrating that it can selectively identify E. coli with the unique selenoenzymes or selenoproteins in the bacterium. After the decomposition of GNRs-SH-NB, the obtained GNRs modified by N-heterocyclic sulfhydryl compounds and positively charged fluorescent dyes showed synergistic antibacterial properties. Furthermore, the photothermal effect of GNRs increased the temperature beyond the optimum temperature of E. coli and caused its maladjustment, leading to the death of the bacterium. Thus, GNRs-SH-NB exerted a considerable antibacterial effect against E. coli and accurately detected E. coli in milk, meat, and eggshell. With the low limit of detection, this novel antibacterial sensor GNRs-SH-NB provide a promising method to identify the E. coli and further utilized in food safety field initially.

Synergistic Antibacterial Effect of Casein-AgNPs Combined with Tigecycline against Acinetobacter baumannii.

Acinetobacter baumannii (A. baumannii) is a common and challenging pathogen of nosocomial infections, due to its ability to survive on inanimate objects, desiccation tolerance, and resistance to disinfectants. In this study, we investigated an antibacterial strategy to combat A. baumannii via the combination of antibiotics and silver protein. This strategy used a functional platform consisting of silver nanoparticles (AgNPs) resurrected from silver-based calcium thiophosphate (SSCP) through casein and arginine. Then, the silver protein was combined with tigecycline, the first drug in glycylcycline antibiotic, to synergistically inhibit the viability of A. baumannii. The synergistic antibacterial activity was confirmed by the 96-well checkerboard method to determine their minimum inhibitory concentrations (MIC) and calculated for the combination index (CI). The MIC of the combination of silver protein and tigecycline (0.31 mg/mL, 0.16 µg/mL) was significantly lower than that of the individual MIC, and the CI was 0.59, which indicates a synergistic effect. Consequently, we integrated the detailed synergistic antibacterial properties when silver protein was combined with tigecycline. The result could make for a promising approach for the treatment of A. baumannii.

Synthesis and Characterization of Selenium Nanoparticles-Lysozyme Nanohybrid System with Synergistic Antibacterial Properties

In the light of promising potency of selenium nanoparticles in biomedical applications, this is the first study to report the synergistic antibacterial activity of these nanoparticles and lysozyme. The nanohybrid system was prepared with various concentrations of each component. Resistance of Escherichia coli and Staphylococcus aureus was compared in the presence of individual Nano and Bio counterparts as well as the nanohybrid system. Upon interaction of SeNPs with Lysozyme, the nanohybrid system efficiently enhanced the antibacterial activity compared to the protein. Therefore, SeNPs play an important role in inhibition of bacterial growth at very low concentrations of protein; whereas very high amount of the protein is required to inhibit bacterial growth individually. On the other hand, lysozyme has also played a vital role in antibacterial property of SeNPs, inducing 100% inhibition at very low concentration of each component. Hence, presence of both nano and bio counterparts induced vital interplay in the Nanohybrid system. The aged samples also presented good stability of SeNPs both as the intact and complex form. Results of this effort highlight design of nanohybrid systems with synergistic antibacterial properties to overcome the emerging antibiotic resistance as well as to define fruitful applications in biomedicine and food safety.

Enhanced Antibacterial Activity of Ag Nanoparticle-Decorated ZnO Nanorod Arrays

Silver (Ag) has broad-spectrum antibacterial properties and is widely used in various fields, including in antibacterial coatings for orthopedic implants. For reasons of cost and cytotoxicity, improvement of the antibacterial efficiency of Ag is necessary. The scientific community has also shown a strong enthusiasm in this research area. In this paper, ZnO nanorod arrays were prepared on a titanium (Ti) substrate by seed-assisted hydrothermal method and Ag nanoparticles were deposited by magnetron sputtering to obtain Ag nanoparticle-decorated ZnO nanorod arrays (ZnO nanorods/Ag nanoparticles). The antibacterial properties of ZnO nanorods/Ag nanoparticles against Pseudomonas aeruginosa were systematically studied by agar diffusion method and were compared with other samples such as ZnO nanorod arrays and ZnO seed layer/Ag nanoparticles. The experimental results showed that ZnO nanorods/Ag nanoparticles displayed significantly higher antibacterial properties against Pseudomonas aeruginosa than other samples, including ZnO nanorod arrays and ZnO seed layer/Ag nanoparticles. These superior antibacterial properties originated predominantly from the morphological structure of ZnO nanorods, which optimized the particle size and distribution of Ag nanoparticles, greatly improving their antimicrobial efficiency. The synergistic antibacterial properties of Ag nanoparticles and ZnO nanorods make Ag nanoparticle-decorated ZnO nanorod arrays a promising candidate for antibacterial coating of orthopedic implants.

N-(Sulfamoylbenzoyl)-L-proline Derivatives as Potential Non-β-lactam ESBL Inhibitors: Structure-Based Lead Identification, Medicinal Chemistry and Synergistic Antibacterial Activities

There is an urgent need to develop novel inhibitors against clinically widespread extended-spectrum β-lactamases (ESBLs) to meet the challenges of the ever-evolving threat of antibiotic resistances. Most existing ESBL inhibitors sharing a common chemical feature of β-lactam ring in their molecule, this structural characteristic makes them intrinsically susceptible to enzymatic breakdown by the resistance mechanisms employed by the bacteria. The aim of this study was to screen and discover novel lead compounds by using Lproline as initial scaffold to create a "non-sulfur, non-β-lactam" new chemotypes for potential ESBL inhibitors. Structure-based molecular docking and virtual screening were employed in the novel inhibitor generation process for lead compound screening and SAR analysis. Evaluation of the ESBL inhibitory activity of the lead compounds was performed in combination with three of the most susceptible antibiotics: ceftazidime, meropenem and ampicillin, against thirteen ESBL enzymes including four new CTX-M harboring strains and four KPC-2 producing species. L-proline derived (S)-1-(2-sulfamoylbenzoyl)pyrrolidine-2-carboxylic acid (compound 6) as a "non-sulfur, non-β-lactam" and the most potential ESBL inhibitor was identified. Compound 6 possesses ideal anti-resistance activities by reducing MICs of ceftazidime, meropenem and ampicillin by 16-133, 32-133 and 67-267 fold respectiveily. The inhibitory mechanism of 6 with CTX-M, KPC-2 and penicillinase were proposed and probed with molecular docking analysis. Given that the simple proline derivative but promising synergistic antibacterial properties of compound 6 augers well for further investigations into its in vivo efficacy.